Swansea chairman Huw Jenkins has resigned after 17 years in the role.
Jenkins, 55, who presided over the club's rise from the bottom tier to the Premier League after being appointed in 2002, announced his decision in a statement.
Swansea escaped relegation out of the Football League in 2003 and won promotion to the Premier League in 2011. They also lifted the League Cup in 2013.
American businessmen Jason Levien and Steve Kaplan bought a 68 per cent stake in Swansea in the summer of 2016 and Jenkins stayed on in his role as chairman.
But the owners have been accused by the Swansea City Supporters' Trust of lacking ambition and pressure from fans has mounted following relegation to the Sky Bet Championship in May.
The Welsh club's 2-0 defeat at Bristol City on Saturday left them 13th in the table, six points off the play-off places.